Not exactly a fish, and lacking a spine, this creature has a single body cavity or mouth.
Not exactly a fish, and lacking a spine, this creature has a single body cavity or mouth.
这种生物既非鱼类，又缺少脊椎，它只有一个体腔，或者也可称之为嘴巴。
Not exactly a fish, and lacking a spine, this creature has a single body cavity or mouth.
这种生物既非鱼类，又缺少脊椎，它只有一个体腔，或者也可称之为嘴巴。